Recently, a technology for adjusting elasticity of a soft material such as a structure for animal cell has been focused on. As the technology for adjusting elasticity of a soft material, the prior art described below is known.
(1) Technologies for adjusting elasticity using temperature control, such as a method in which elasticity of rubber is arbitrarily changed due to temperature (for example, refer to Patent Document 1) and a method in which elasticity of a separation membrane is adjusted by heat (for example, refer to Patent Document 2).
(2) Technologies for adjusting elasticity using a crosslinking density or a crosslinking method, such as a method in which a body formed using a collagen, a proteoglycan and a hyaluronic acid is subjected to thermal dehydration crosslinking, and thus elastic modulus of a predetermined level or higher thereof is maintained (for example, refer to Patent Document 3), a method in which a collagen gel having high elasticity used as a scaffold material is obtained by crosslinking using a chemical method or a physical method (for example, refer to Patent Document 4), a method in which crosslinking conditions of a collagen are changed, and thus elastic modulus of a collagen gel used as a cell lead-out substrate is adjusted (for example, refer to Patent Document 5), and a method in which a crosslinking (photocrosslinking) density of a hyaluronic acid gel is changed to adjust elastic modulusi of the hyaluronic acid gel (for example, refer to Patent Document 6).
(3) Technologies for adjusting elasticity by adding and dispersing an inorganic material, such as a method in which a clay mineral is dispersed in an acrylamide-based monomer to adjust elastic modulus of a polymer hydrogel which is obtained after polymerization thereof (for example, refer to Patent Document 7).
(4) Technologies for adjusting elasticity by performing a three-dimensional structure control, such as a method in which a collagen is porosified and thus elasticity is adjusted (for example, refer to Patent Document 8).
In addition, cells are known to have a tendency to migrate from a surface having a low elastic modulus to a surface having a high elastic modulus (for example, refer to Non-Patent Documents 1 to 8). As the prior art in which elasticity of a surface of a structure used for animal cell is selectively adjusted, a method in which an area in which a concentration of a crosslinking agent is different is arranged when a structure used for animal cell is manufactured (for example, refer to Non-Patent Documents 1 to 7) and a method using local photocrosslinking (for example, refer to Non-Patent Document 8) are known.
Furthermore, a technology for controlling a migration speed of cells (for example, refer to Non-Patent Documents 1, and 9 to 13), a technology for controlling a proliferation rate of cells (for example, refer to Non-Patent Document 14), a technology in which a morphological change of cells resulting from a change in elastic modulus of a surface is used (refer to Non-Patent Documents 2, 9, and 14 to 16), and a technology in which a change in a degree of differentiation and a change in a differentiation direction of cells resulting from a difference of elastic modulus of a surface are used (refer to Non-Patent Documents 17 to 22) are known.